The aim of this study was to fabricate multi-layered recycled α-Fe<sub>2</sub>O<sub>3</sub>/OPEFB fiber/PCL composites for microwave absorbing applications in the 1 - 4 GHz frequency range. Th...The aim of this study was to fabricate multi-layered recycled α-Fe<sub>2</sub>O<sub>3</sub>/OPEFB fiber/PCL composites for microwave absorbing applications in the 1 - 4 GHz frequency range. The multi-layered composites were 6 mm thick and each consisted of a 2 mm thick layer of recycled α-Fe<sub>2</sub>O<sub>3</sub>/PCL composites at various loadings (5 wt% - 25 wt%) of 16.2 nm recycled α-Fe<sub>2</sub>O<sub>3</sub> nanofiller, placed between two layers of 2 mm thick OPEFB fiber/PCL composites blended at a fixed ratio of 7:3. The real (ε') and imaginary (ε") components of the relative complex permittivity were measured using the open-ended coaxial probe technique and the values obtained were applied as inputs for the Finite Element Method to calculate the reflection coefficient magnitudes from which the reflection loss (RL) properties were determined. Both ε' and ε" increased linearly with recycled α-Fe<sub>2</sub>O<sub>3</sub> nanofiller content and the values of ε' varied between 3.0 and 3.9 while the ε" values ranged between 0.26 and 0.64 within 1 - 4 GHz. The RL (dB) showed the most prominent values within the 1.38 - 1.46 GHz band with a minimum of -38 dB attained by the 25 wt% composite. Another batch of minimum values occurred in the 2.39 - 3.49 GHz range with the lowest of -25 dB at 2.8 GHz. The recycled α-Fe<sub>2</sub>O<sub>3</sub>/OPEFB fiber/PCL multi-layered composites are promising materials that can be engineered for solving noise problems in the 1 - 4 GHz range.展开更多
Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinit...Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinity correlates with greater strength and stiffnes,but it can reduce the water-holding capacity.The acid concentration and hydrolysis time will affect the acquisition of crystallinity and water absorption capacity,both of which have significance as properties of hydrogel filler.The study aimed to evaluate the properties and select the MCC generated from varying the proportion of hydrochloric acid(HCl)and the appropriate hydrolysis time as a filler for film hydrogel.MCC was produced by hydrolyzing cellulose of oil palm empty fruit bunches(OPEFB)with the HCl solution at varied concentrations and periods.The results show that the longer hydrolysis times and higher HCl concentrations increase crystallinity and density while lowering yield and water absorption.The extensive acid hydrolysis reduces the amorphous area significantly,allowing the depolymerization to occur and extend the crystalline area.The morphological properties of the MCC,which are smaller but compact,indicate the presence of disintegrating and diminishing structures.A 2.5 N HCl concentration and a 45-min hydrolysis time succeed in sufficient crystallinity as well as maintaining good water absorption capacity.The treatment produced MCC with absorption capacity of 4.03±0.26 g/g,swelling capacity of 5.03±0.26 g/g,loss on drying of 1.44%±0.36,bulk and tapped density of 0.27±0.031 g/cm^(3) and 0.3±0.006 g/cm^(3),respectively,with a crystallinity index of 88.89%±4.76 and a crystallite size of 4.23±0.70 nm.The MCC generated could potentially be utilized as a hydrogel film filler,since a given proportion will be able to maintain the strength of the hydrogel,not readily dissolve but absorb water significantly.展开更多
One of the impacts resulting from mining process is the occurrence of AMD(Acid Mine Drainage),which is rainwater or groundwater mixed with rock.AMD contains specific sulfides in coal,leading to highly acidic water wit...One of the impacts resulting from mining process is the occurrence of AMD(Acid Mine Drainage),which is rainwater or groundwater mixed with rock.AMD contains specific sulfides in coal,leading to highly acidic water with elevated concentrations of iron and manganese.Furthermore,phytoremediation offers a method to enhance specific contaminant levels in various environmental mediums,including soil,sediment,dirt or sludge,groundwater,and surface water.This waste treatment approach employs readily applicable,efficient,and effective plant species,such as burhead or Amazon sword,Melati air(Echinodorus palaefolius),Water hyacinth or eceng gondok(Eichhornia crassipes),and globe fimbry or Mendong(Fimbritylis globulosa)which are aquatic plants in South Sumatra with the capacity to absorb heavy metals.Therefore,this study aims to measure the growth response of each aquatic plant(Echinodorus palaefolius,Eichhornia crassipes,and Fimbritylis globulosa)in each treatment.It also analyzes the amount of heavy metal uptake in the form of Fe and Mn by each aquatic plant(Eichhornia crassipes,Echinodorus palaefolius,and Fimbritylis globulosa)used.Additionally,it investigates the ability of these plants to facilitate the phytoremediation of AMD using compost derived from OPEFB(Oil Palm Empty Fruit Bunches)to reduce the presence of Fe and Mn elements.The study employs a bioreactor and encompasses two treatment factors,namely the type of aquatic plants(Echinodorus palaefolius,Eichhornia crassipes,and Fimbritylis globulosa)and the composition comparison between OPEFB compost and limestone.The result shows that the combination of treatments in terms of plant types and media composition yields the highest growth,with a weight of 286.25 g in T2K1 treatment.This involves Eceng gondok and a media composition of compost to limestone in a ratio of 50%to 50%.Moreover,Mendong exhibits the highest absorption of Fe metal,with a value of 0.82 g,followed by Eceng gondok with 0.55 g,while Melati displays the lowest at 0.38 g.Regarding the absorption of Mn,Eceng gondok demonstrates the highest uptake,measuring 0.36 g,followed by Melati and Mendong at 0.11 g and 0.06 g,respectively.展开更多
文摘The aim of this study was to fabricate multi-layered recycled α-Fe<sub>2</sub>O<sub>3</sub>/OPEFB fiber/PCL composites for microwave absorbing applications in the 1 - 4 GHz frequency range. The multi-layered composites were 6 mm thick and each consisted of a 2 mm thick layer of recycled α-Fe<sub>2</sub>O<sub>3</sub>/PCL composites at various loadings (5 wt% - 25 wt%) of 16.2 nm recycled α-Fe<sub>2</sub>O<sub>3</sub> nanofiller, placed between two layers of 2 mm thick OPEFB fiber/PCL composites blended at a fixed ratio of 7:3. The real (ε') and imaginary (ε") components of the relative complex permittivity were measured using the open-ended coaxial probe technique and the values obtained were applied as inputs for the Finite Element Method to calculate the reflection coefficient magnitudes from which the reflection loss (RL) properties were determined. Both ε' and ε" increased linearly with recycled α-Fe<sub>2</sub>O<sub>3</sub> nanofiller content and the values of ε' varied between 3.0 and 3.9 while the ε" values ranged between 0.26 and 0.64 within 1 - 4 GHz. The RL (dB) showed the most prominent values within the 1.38 - 1.46 GHz band with a minimum of -38 dB attained by the 25 wt% composite. Another batch of minimum values occurred in the 2.39 - 3.49 GHz range with the lowest of -25 dB at 2.8 GHz. The recycled α-Fe<sub>2</sub>O<sub>3</sub>/OPEFB fiber/PCL multi-layered composites are promising materials that can be engineered for solving noise problems in the 1 - 4 GHz range.
基金the Universitas Gadjah Mada’s financial support for this research.This research was conducted using the Final Project Recognition Grant Universitas Gadjah Mada Indonesia Number of 5075/UN1.P.II/DitLit/PT.01.01/2023.
文摘Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinity correlates with greater strength and stiffnes,but it can reduce the water-holding capacity.The acid concentration and hydrolysis time will affect the acquisition of crystallinity and water absorption capacity,both of which have significance as properties of hydrogel filler.The study aimed to evaluate the properties and select the MCC generated from varying the proportion of hydrochloric acid(HCl)and the appropriate hydrolysis time as a filler for film hydrogel.MCC was produced by hydrolyzing cellulose of oil palm empty fruit bunches(OPEFB)with the HCl solution at varied concentrations and periods.The results show that the longer hydrolysis times and higher HCl concentrations increase crystallinity and density while lowering yield and water absorption.The extensive acid hydrolysis reduces the amorphous area significantly,allowing the depolymerization to occur and extend the crystalline area.The morphological properties of the MCC,which are smaller but compact,indicate the presence of disintegrating and diminishing structures.A 2.5 N HCl concentration and a 45-min hydrolysis time succeed in sufficient crystallinity as well as maintaining good water absorption capacity.The treatment produced MCC with absorption capacity of 4.03±0.26 g/g,swelling capacity of 5.03±0.26 g/g,loss on drying of 1.44%±0.36,bulk and tapped density of 0.27±0.031 g/cm^(3) and 0.3±0.006 g/cm^(3),respectively,with a crystallinity index of 88.89%±4.76 and a crystallite size of 4.23±0.70 nm.The MCC generated could potentially be utilized as a hydrogel film filler,since a given proportion will be able to maintain the strength of the hydrogel,not readily dissolve but absorb water significantly.
文摘One of the impacts resulting from mining process is the occurrence of AMD(Acid Mine Drainage),which is rainwater or groundwater mixed with rock.AMD contains specific sulfides in coal,leading to highly acidic water with elevated concentrations of iron and manganese.Furthermore,phytoremediation offers a method to enhance specific contaminant levels in various environmental mediums,including soil,sediment,dirt or sludge,groundwater,and surface water.This waste treatment approach employs readily applicable,efficient,and effective plant species,such as burhead or Amazon sword,Melati air(Echinodorus palaefolius),Water hyacinth or eceng gondok(Eichhornia crassipes),and globe fimbry or Mendong(Fimbritylis globulosa)which are aquatic plants in South Sumatra with the capacity to absorb heavy metals.Therefore,this study aims to measure the growth response of each aquatic plant(Echinodorus palaefolius,Eichhornia crassipes,and Fimbritylis globulosa)in each treatment.It also analyzes the amount of heavy metal uptake in the form of Fe and Mn by each aquatic plant(Eichhornia crassipes,Echinodorus palaefolius,and Fimbritylis globulosa)used.Additionally,it investigates the ability of these plants to facilitate the phytoremediation of AMD using compost derived from OPEFB(Oil Palm Empty Fruit Bunches)to reduce the presence of Fe and Mn elements.The study employs a bioreactor and encompasses two treatment factors,namely the type of aquatic plants(Echinodorus palaefolius,Eichhornia crassipes,and Fimbritylis globulosa)and the composition comparison between OPEFB compost and limestone.The result shows that the combination of treatments in terms of plant types and media composition yields the highest growth,with a weight of 286.25 g in T2K1 treatment.This involves Eceng gondok and a media composition of compost to limestone in a ratio of 50%to 50%.Moreover,Mendong exhibits the highest absorption of Fe metal,with a value of 0.82 g,followed by Eceng gondok with 0.55 g,while Melati displays the lowest at 0.38 g.Regarding the absorption of Mn,Eceng gondok demonstrates the highest uptake,measuring 0.36 g,followed by Melati and Mendong at 0.11 g and 0.06 g,respectively.
